quantum physics

The philosopher in the street, who has not suffered a course in quantum mechanics, is quite unimpressed by the [Einstein-Podolsky-Rosen] correlations. He can point to many examples of similar correlations in everyday life. The case of Bertlmann’s socks is often cited. Dr. Bertlmann likes to wear two socks of different colours. Which colour he will have on a given foot on a given day is quite unpredictable. But when you see that the first sock is pink you can be already sure that the second sock will not be pink. Observation of the first, and experience with Bertlmann, gives the immediate information about the second. There is no accounting for tastes, but apart from that there is no mystery here. And is this [Einstein-Podolsky-Rosen] business just the same?

John Bell began his now famous paper with the above paragraph. The Bell Inequality started off like so many other great theories in science – as a simple thought experiment. Its conclusions were not so simple, however, and would lead the way to the end of Einstein’s idea of local hidden variables, and along with it his hopes for a deterministic universe. In this article, we’re going to look at the Bell inequality in great detail. Our guide will be a chapter from Jim Baggots’ The Quantum Story, as it has one of the best descriptions of Bell’s theory I’ve ever read.

Week 16 of the Caption CERN Contest just flew by, but not without sparking some cosmic comic genius in the minds of everyone who wrote a comment. Thanks to everyone who entered! If you followed last week’s blog post, you already know that this image isn’t an early POV display, or some sort of strange data display technique. It’s actually a spark chamber. Spark chambers use high voltage and noble gases to create a visible trail of cosmic rays. Since this image is dated 1979, well after spark chambers were used for hard science, we’re guessing it was part of a demonstration at CERN’s labs.

The Funnies:

“Here we see Doug playing a Massively multiplayer Pong game against his peers in the next building over.” – [John Kiniston]

“It said “Would you like to play a game?” and I said yes. Are those missile launch tracks?”- [jonsmirl]

“Before Arduino you needed a whole room full of equipment to blink LEDs!” – [mjrippe]

After two weeks as a runner-up, this week’s winner is The Green Gentleman with “‘Hang on, let me fix the vert-hold, and then get ready for a most RIGHTEOUS game of 3D PONG!’ Sadly, this CERN spinoff never made it to the market”

We’re sure [The Green Gentleman] will be very courteous to his fellow hackers in sharing his new Bus Pirate From The Hackaday Store! Congratulations [The Green Gentleman]!

Week 17

Coils, gleaming metal, giant domes, now this is a proper mad scientist image! The CERN scientists in this image seem to be working on a large metal device of some sort. It definitely looks like an electrode which would be at home either at CERN or the well equipped home lab of one Dr. Frankenstein’s. We don’t have a caption, but we do have a rough date of August, 1961. What is happening in this image? Are these scientists setting up an experiment, or plotting world domination?

[Limpkin] designs circuits for a living. This board is one of his recent projects, and although his skills are light years ahead of our own experiences, he did a pretty good job of explaining how he put this board together.

He was tasked with measuring the light intensity of two photodiodes. The expected impulses picked up by those components will be less than a nanosecond in duration, putting some special design constraints upon him. To register this signal he’s using three cascading op-amps per input. To ward off false readings from RF interference he also designed in the shielding which you see surrounding the majority of the circuit.

His package choice for the THS3202 op-amps is quite interesting. He didn’t go with the footprint that includes a thermal pad to dissipate heat because he didn’t want to interrupt the ground plane on the underside of the board. To keep the parts from melting he added an aluminum spacer that contacts the top of the package, then a heat sink that covers the entire shield frame. In a future revision he figures he’ll move to a four-layer board so that the can opt for the MSOP package that does the work for him.